1. Field of the Invention
This invention relates to a sunroof and, more particularly, to improvements in an outer sliding-type sunroof.
2. Description of the Prior Art
Sunroof mechanisms for automotive vehicles have become popular in recent years. Specifically, the roof panel of an automotive vehicle is provided with an opening which can be opened and closed by sliding a sliding panel manually or electrically. The popularity of such sunroofs resides in the fact that a vehicle to which a sunroof is attached imparts a sensation of openness to the passengers and greatly improves ventilation within the passenger compartment.
The mechanism which opens and closes the roof panel opening by means of the sliding panel will now be described in brief.
A square housing having a central opening is fixed about the opening in the roof panel of an automotive vehicle. Guide rails extending longitudinally of the vehicle are secured to the left and right sides of the housing, an electric motor serving as a driving source is mounted on the rear portion of the housing, and the inner peripheral surface of the housing is made to serve as a rain trough so that rainwater can be drained to the outside via drain hoses. A shoe situated within each guide rail is installed, each shoe is connected to the sliding panel via a link having a cam mechanism, and the shoe is connected to the motor via a driving cable.
When a passenger switches on the mechanism in an opening direction, the motor is placed in operation and pulls the shoes rearwardly of the vehicle, thereby causing the rearward side of the sliding panel to rise about the front side and assume an upwardly tilted attitude. This upwardly tilted attitude is maintained for a time as the switch continues to be held in the opening direction. If this up-tilted state is desired, the passenger turns off the switch at this time. If it is desired to retract the sliding panel to fully open the roof panel opening, the passenger leaves the mechanism switched on. As a result, the motor continues to operate and retracts the up-tilted sliding panel to open the roof panel opening. This communicates the interior of the passenger compartment with the outside. In order to close the opening, the mechanism is switched on in the closing direction to operate the sliding panel in a manner which is the opposite of that described above.
Weather stripping is fixed to the periphery of the sliding panel. When the sliding panel is in the closed state, the weather stripping provides a seal between the sliding panel and the edge of the roof panel opening and prevents rainwater or the like from intruding into the passenger compartment. Drainage to the exterior is performed by the rain trough of the housing if rainwater should manage to penetrate the weather stripping seal. When the sliding panel is in the up-tilted state, rainwater which has attached itself to the outer surface of the sliding panel is discharged to the outside via the rain trough.
The outer sliding-type sunroof assembly has the basic construction described above. However, certain problems arise with this conventional sunroof assembly. By way of example, in the specification of Japanese Patent Application Laid-Open (KOKAI) No. 60-215423, a locking lever is constituted by a single member, and therefor the lever member is large in size. When a sliding panel is in the fully closed state, the lever must be housed above a guide rail and within the space of the sliding panel. As a result, the guide rail must be lowered, sufficient space cannot be furnished between the sliding panel and the roof, a large amount of headroom cannot be provided and the overall assembly is large in size.
Other problems are encountered as well, as also exemplified in the aforementioned specification of Japanese Patent Application Laid-Open (KOKAI) No. 60-215423. Specifically, a locking link having an implanted locking pin is pivotally attached to the rear end of the lever, and a locking body having a locking groove is riveted to the rear edge portion of the guide rail. When the sliding panel is in the fully closed state, the locking pin is inserted into the locking groove to maintain the sliding panel in the fully closed condition. Thus, a large number of locking members are required, resulting in a complicated structure. The amount of headroom available is diminished accordingly.
Still another problem encountered in the aforementioned specification of Japanese Patent Application Laid-Open (KOKAI) No. 60-215423 is that the lever member is not kept urged forwardly to maintain the prevailing state. Instead, the lever member is left free and therefore is likely to rattle owing to vehicle vibration or the like. In addition, if an accident should occur in which the vehicle rolls over, there is the danger that the locking pin of locking link provided in the end of link member will come out of the locking groove 46 of locking member.
Another difficulty is exemplified in the specification of Japanese Utility Model Application Laid Open (KOKAI) No. 63-114819. Here the sliding panel tends to flutter, when in the up-tilted attitude, owing to the machining precision of a guide shaft fitted into a cam groove as well as wear caused by long use.
Furthermore, in an outer sliding-type sunroof disclosed in the specification of Japanese Utility Model Application Laid-Open (KOKAI) No. 63-119115, movement of a bracket toward the outer side of the vehicle is not limited at the position of a pin. Consequently, position is not decided until the bracket is attached to a sliding panel, and reliability of operation as a guide rail assembly cannot be confirmed by moving a cable. In addition, this is accompanied by a decline in the accuracy with which the bracket is attached to the sliding panel.
Furthermore, in the sliding sunroof assembly having the basic construction described above, the tilt-up or tilt-down motion of the sliding panel is decided by the shape of a cam groove in a cam member. The conventional cam-groove shape is a combination of a straight portion, which is for the back-and-forth movement of a shoe independent of the sliding panel, and a linear inclined portion connected with the straight portion. When a pin in the shoe runs along the inclined portion of the cam groove, the sliding panel tilts in such a manner that the rear portion thereof ascends or descends. In other words, when the pin leaves the straight portion and makes the transition to the inclined portion, the angle of inclination of the sliding panel increases, and generally a maximum inclination angle of 5.degree. can be selected. When the pin of the shoe enters the straight portion, the inclination angle is reduced to zero, i.e., the sliding panel assumes the fully closed state.
When the sliding panel is in the inclined state, air flows from the interior of the passenger compartment to the outside and attempts to raise the sliding panel. In other words, the force of the air drawn from the interior to the exterior of the passenger compartment acts against the operation for closing the sliding panel and, as a result, a larger torque is needed to closed the panel. In particular, as indicated by the straight line in FIG. 20, a large torque is necessary to close the sliding panel in an angular range of 0.degree.-2.degree.. An electric motor capable of providing such a high torque at closing of the panel is large in size and consumes a large amount of power.